INFLUENCES OF ALLOY DISORDER AND INTERFACE ROUGHNESS ON OPTICAL-SPECTRA OF INGAAS/GAAS STRAINED-LAYER QUANTUM-WELLS

We present studies of alloy composition and layer thickness dependences of excitonic linewidths in InGaAs/GaAs strained-layer quantum wells grown by MBE, using both photoluminescence and optical absorption. It is observed that linewidths of exciton spectra increase with indium content and well size. Using the virtual crystal approximation, the experimental data are analyzed. The results obtained show that the alloy disorder is the dominant mechanism for line broadening at low temperature. In addition, it is found that the absorption spectra related to light hole transitions have varied from a peak to a step-like structure as temperature increases. This behavior can be understood by the indirect space transitions of light holes.

第一性原理研究Mg,Si和Mn共掺GaN

采用基于密度泛函理论(DFT)的第一性原理平面波赝势法(PWP)计算Mg,Si和Mn共掺GaN电子结构和光学性质,分析比较计算结果.计算表明:掺杂后体系均在能隙深处产生自旋极化杂质带,具有半金属性,能产生自旋注入.与Mn掺杂GaN比较,Mg共掺后能使居里温度(TC)升高,并在1.0eV出现源于Mn4+离子基态4T1(F)到4T2(F)态跃迁的较强的光吸收,而Mn掺杂GaN时位于1.3eV处的吸收峰消失;Si共掺后没能使TC升高,且在低能区无光吸收现象.

多段式半导体激光器的研究进展

综述了多段式半导体激光器的研究进展。按结构不同，将它们分为两段式、三段式和四段式激光器进行讨论。重点介绍了几类具有典型结构的单片式集成激光器，总结了它们的设计背景、设计目的、基本设计思想、性能特点和基本用途，讨论了这些器件结构的共同点，指出两段式、三段式和四段式激光器研究上的关联和各自的研究重点。分析了多段式半导体激光器的发展趋势，展望了它们的应用前景。

Design and numerical analysis for low birefringence silica on silicon waveguides

A new fabrication technology for three-dimensionally buried silica on silicon optical waveguide based on deep etching and thermal oxidation is presented. Using this method, a silicon layer is left at the side of waveguide. The stress distribution and effective refractive index are calculated by using finite element method and finite different beam propagation method, respectively. The results indicate that the stress of silica on silicon optical waveguide fabricated by this method can be matched in parallel and vertical directions and stress birefringence can be effectively reduced due to the side-silicon layer.

Investigation of Residual Donor Defects in Undoped and Fe-Doped LEC InP

The free electron concentration of as-grown liquid encapsulated Czochralski (LEC) InP measured by Hall effect is much higher than the concentration of net donor impurity determined by glow discharge mass spectroscopy. Evidence of the existence of a native donor hydrogen-indium vacancy complex in LEC undoped and Fe-doped InP materials can be observed with infrared absorption spectra. The concentration increase of the donor complex correlates with the increase of ionized deep acceptor iron impurity Fe~(2+) concentration in Fe-doped semi-insulating (SI) InP. These results indicate that the hydrogen-indium vacancy complex is an important donor defect in as-grown LEC InP, and that it has significant influence on the compensation in Fe-doped SI InP.

Ramping热退火直拉重掺锑硅衬底片的增强氧沉淀

该文报道了一种改进本征吸杂技术－－低温短时热退火工艺，以增强本征吸杂效果，在本征吸杂工艺的低温热退火中，用连续的线性缓慢升温(Ramping)退火替代常规的长时间低温恒温退火，应用于直拉(CZ)重掺N型硅衬底片，明显增加了氧沉淀等体微缺陷密度，这些高密度氧沉淀物在随后IC器件工艺中继续长大，成为稳定的高效本征吸杂中心。从经典的成核沉淀理论,讨论了Ramping热退火重掺硅衬底片增强氧沉淀机理。